1. Field of the Invention
The present invention relates to a yarn winder which winds a yarn at a speed not less than 4000 m/min, and more particularly relates to a controlling system for driving the yarn which can wind the yarn at high speed.
2. Description of the Related Art
In general, when a yarn is wound after it has been spun out from a spinning machine, a winder is used which includes: a spindle to which a tube is attached, wherein the spindle is rotatably mounted on a machine frame; a traverse unit disposed at an upper position of the spindle, wherein the traverse unit can be elevated in a vertical direction with respect to the machine frame; and a pressure roller coming into contact with a tube attached to the spindle so that a predetermined surface pressure can be given to the tube.
In the case where the winding speed is not less than 6000 m/min, the spindle and pressure roller are positively rotated by a drive unit for preventing the tube surface from being damaged when it is rubbed by the pressure roller, and also even in the case where the winding speed is 4000 m/min to 6000 m/min, the spindle and pressure roller are positively rotated for improving a package configuration.
When the spindle rotating at the high speed described above is switched from a fully loaded tube to an empty tube, the speed of the fully loaded tube is slightly increased and the winding tension is increased so that the yarn can be more strongly wound in yarn catching grooves formed on the tube, and so that the yarn tension can be stabilized for preventing the yarn from being wound around a godet roller disposed on the upstream side of the winder.
However, in the case where the pressure roller is driven at a predetermined speed, a yarn on the upstream side of the winder is wound by the fully loaded tube after it has come into contact with the pressure roller. Therefore, when an increase of the speed of the fully loaded tube is small, tension of the yarn on the upstream side of the winder is not increased, so that the yarn is wound around the godet roller due to a decrease of tension when the yarn is switched. In this way, the yarn switching operation fails. When the increase of the speed of the fully loaded tube is large, tension applied between the pressure roller and the fully loaded tube is greatly increased, so that the yarn is torn off when it comes into contact with the tube. In this way, the yarn switching operation also fails. Further, a problem is caused in which the yarn tension fluctuates in the case where the yarn is switched so that the characteristics of the yarn wound in the most outside layer are changed.
In an ordinary yarn taking up operation, and yarn switching operation, including the yarn which is spun from a nozzle of a yarn spinning machine, is directly wound on an empty tube rotated at a high speed, at time when the yarn is first set on the tube or when the yarn is first switched, the thickness of a yarn layer wound around the tube is very small. Therefore, when the pressure roller comes into contact with the yarn layer on the tube under the above condition, the yarn layer is beaten and damaged by the pressure roller, which causes weaving specks in a weaving process and dyeing specks in a dyeing process.
In order to prevent the occurrence of the above problems in which the yarn layer is beaten and damaged by the pressure roller when the pressure roller comes into contact with the yarn layer on the tube under the condition that the yarn layer on the tube is very thin, the pressure roller is provided with a step portion, and a pacer is provided at an end portion of a sliding shaft supporting the pressure roller so that a gap can be formed between the pressure roller and the tube.
Further, the pressure roller described above is positively rotated by a drive unit, so that the pressure roller is not contacted with the yarn layer when the yarn is set on the drum or when the yarn is switch or immediately after the switch of the yarn. For this reason, it is impossible to control the rotational speed of the spindle to which the tube is attached, in accordance with the rotational speed of the pressure roller.
Therefore, until the pressure roller comes into contact with the yarn layer, the spindle speed is controlled by forward control based on the calculation of a diameter of the yarn layer wound around the tube utilizing a conventional manner. This forward control is switched to feedback control in the following manner: When a yarn layer of predetermined thickness is formed on the tube, the yarn layer comes into contact with the pressure roller so that the rotational speed (number of revolution) of the spindle is changed. Then the change in speed is detected, and the rotational speed control of the spindle is switched to feedback control in which the rotational speed of the spindle is controlled to a predetermined winding speed in accordance with the rotational speed of the pressure roller.
According to a method in which the pressure roller is supported at a predetermined position and the yarn layer comes into contact with the pressure roller when a diameter of the yarn layer is increased as the yarn is wound around the tube, as illustrated in FIG. 17, it takes a very long period of time from a point of time (T1) when the yarn layer is formed on the tube and the yarn layer on the tube starts coming into contact with the pressure roller, to a point of time (T3) when the surface pressure is increased to a predetermined surface pressure (Pa).
Even when the yarn layer comes into contact with the pressure roller, the surface pressure varies according to the type, size and layer thickness of the yarn, and further the rotational condition of the pressure roller also varies.
For this reason, it is impossible to accurately detect the time at which feed forward control is switched to feedback control, and further the following problems are caused: Even when the surface pressure is not increased to the setting surface pressure (Pa), feed forward control is switched to feedback control. Even after the surface pressure has increased to the predetermined surface pressure (Pa), feed forward control can not be switched to feedback control. In this way, speed control can not be conducted accurately, so that a difference is produced between the surface speeds of the yarn layer and the pressure roller. Accordingly, the yarn layer is affected.
In this case, the pressure roller is driven by an electric motor controlled by open loop control so that the rotational speed of the pressure roller can become a value corresponding to the setting speed.
When the spindle provided with a tube is rotated by the electric motor and the pressure roller comes into contact with the tube, winding of the yarn starts. Then the rotational speed of the pressure roller is detected, and the electric motor for driving the spindle is subjected to feedback control so that the pressure roller speed can be a predetermined value.
There is a slippage in the rotation of the electric motor itself, and further there is a rotational resistance in the rotation of the bearing portion of the electric motor, and also there is a rotational resistance in the rotation of the bearing portion of the roller. Accordingly, when the drive of the electric motor is controlled without giving consideration to the slippage, the virtual rotational speed of the pressure roller is lowered with respect to the directed rotational speed of the electric motor. As a result, the pressure roller is driven by the spindle, so that an extra load is applied to a package, which deteriorates the configuration of the package.
Different from the above case, in a turret type winder in which the electric motor for driving the pressure roller is subjected to open loop control, when the pressure roller is not contacted with the package in the case where the yarn is switched, the rotational speed of the pressure roller is not corrected even if the virtual rotational speed of the pressure roller is lowered with respect to the directed rotational speed. Consequently, the yarn winding tension is lowered.
When the yarn is switched from a fully loaded package to an empty package under the above condition, the yarn is wound around the rollers arranged on the upstream side of the winder, so that the success ratio of switching a yarn is lowered.
In order to solve the above problems, a slippage caused in the electric motor for driving the pressure roller is measured after the completion of assembly of the winder in the manufacturing process, and the measured slippage is converted into a correction coefficient, which is manually inputted into the control unit so as to be stored.
Further, the following winder is used when a yarn is wound after it has been spun out from a spinning machine. The winder includes: a spindle rotatably attached to a machine frame, the spindle holding a plurality of tubes; a pressure roller coming into contact with a yarn layer wound around the tube held by the spindle; a traverse unit disposed on an upstream side of the pressure roller; a frame body to which the pressure roller is rotatably attached and also the traverse unit is integrally attached, the frame body being supported by two guides provided in the machine frame in a cantilever condition so that the frame body can be vertically elevated; and a hydraulic cylinder supporting a portion of the frame body close to the cantilever portion. The winder having the above construction is disclosed in the official gazette of Japanese Utility Model Publication No. 57-57091.
Recently, in order to improve the winding capacity, the spindle length is increased so that the number of tubes to be held by the spindle can be increased (the number is increased to 4 to 8). When the spindle length is increased, the length of a pressure roller and that of a traverse unit are naturally increased.
However, a frame body to which the pressure roller and the traverse unit are attached is supported in a cantilever condition by two guides provided in the machine frame.
Therefore, as illustrated in FIG. 18, when the length from a gravity center (G) of the frame body 71 to the hydraulic cylinder 74 is L1, and the weight of the frame body 71 and the pressure roller is W, the moment (W.times.L1) is applied to the sliding ball bearing 73 by which the frame body 71 is slidably provided to the guide 72. For example, when the weight (W) of the frame body 71 and others is 200 Kg, and the length (L1) from the gravity center (G) of the frame body 71 to the hydraulic cylinder 74 is 90 cm, the moment of 18000 Kg.multidot.cm is applied to the sliding ball bearing 73.
When the large moment described above is applied to the sliding ball bearing 73, the running resistance of the sliding ball bearing 73 is increased, and the surface pressure of a pressure roller (not shown) can not be correctly controlled, so that the configuration of a package is deteriorated.
In order to allow it to receive such a high moment, the diameter and length of the sliding ball bearing 73 are greatly increased. Therefore, the height of the frame body 71 on which the sliding ball bearing is mounted must be increased, so that the overall length of the winder is increased.
In this connection, when a yarn is wound by the winder described above, since the spindle is mounted on the same machine frame as that of the frame body, vibration is transmitted to the frame body through the machine frame when the spindle is rotated. Further, since the pressure roller is contacted with the tube held by the spindle with a predetermined surface pressure, vibration of the spindle is transmitted to the frame body through the pressure roller.
Therefore, when the frequency of vibration caused by the rotation of the spindle winding a yarn coincides with the natural frequency of the frame body, the frame body resonates, so that the vibration is increased, which causes the collapse of the yarn layer of the package.
In the case where the winding operation is not conducted by the above winder, it is necessary to fix the pressure roller to the machine frame so that the pressure roller can not come into contact with the tube held by the spindle under the condition that hydraulic fluid is not supplied to a hydraulic cylinder. Therefore, as illustrated in FIG. 18, a stopper means 75 is provided at a position of the fore end of the frame body 71, wherein the position is located closer to the fore end than the cantilever supporting portion of the frame body 71.
The stopper means 75 is rotatably mounted on the machine frame 70, and composed of an engaging claw member 76 rotated by a hydraulic cylinder 77, and an engaging piece 78 integrally attached to the frame body 71. When the engaging piece 78 is hooked at the engaging claw member 76, the frame body 71 is supported so that it can not be lowered.
Therefore, in the same manner as that of a case in which the frame body 71 is supported by the hydraulic cylinder 74, when the length from the gravity center (G) of the frame body 71 to the hook position (G1) of the stopper means 75 is L1, and the length from the hook position (G1) of the stopper means 75 to the center of the guide 72 is L3, and the weight of the frame body 71 is w, the same moment (W.times.L1) as that applied to the sliding ball bearing 73 when the frame body 71 is supported by the hydraulic cylinder 74, is applied to the sliding ball bearing 73.
Therefore, a sliding ball bearing 73, the allowable moment of which is high, must be used for this device, so that the size of the frame body 71 is increased in the height direction in the same manner as that of the case described above. Accordingly, an overall height of the winder is increased.
In this connection, Japanese Unexamined Utility Model Publication No. 5-12454 discloses a construction in which guides are provided on both sides of the frame body, and the frame body is elevated along the two guides while both sides of the frame body are supported by the guides.
However, in order to elevate the long frame body in parallel with respect to the spindle while both ends of the frame body are supported by the guides, it is necessary to accurately machine the frame body and guides, and further predetermined rigidity is required for the frame body and guides.
Further, in order to maintain the pressure roller and spindle parallel with each other without being affected by the condition of the floor on which the winder is installed, it is necessary to increase the sizes of the machine frame, guides and frame body.
In this connection, the construction of a drive type pressure roller is shown in FIG. 19, in which the pressure roller is positively rotated. The drive type pressure roller is constructed in the following manner: One shaft portion 81b of the roller 81 is rotatably provided in the frame body 95 for mounting the traverse head, through the bearing section 82. The other shaft portion 81c is rotatably supported by the bearing section 87, and connected with the electric motor 89 through the coupling 88. The bearing section 82 is composed of the bearing 83 rotatably supporting the shaft portion 81b of the roller 81, and also composed of the bracket 84 which is a supporting member of the bearing 83. The bearing section 85 is composed of the bearing 86 rotatably supporting the shaft portion 81c, and also composed for the bracket 87 which is a supporting member of the bearing 86.
Alternatively, the construction of a drive type pressure roller is shown in FIG. 20, in which the drive type pressure roller is constructed in the following manner: Both shaft portions 81b, 81c of the roller 81 are rotatably supported by the frame body 95 through the bearing 82. One shaft portion 81c is provided with the timing pulley 90, and the output shaft of the electric motor 89 mounted on the frame body is provided with the timing pulley 91. The timing belt 92 is provided between the timing pulleys 90, 91. Rotation is transmitted to the roller 81 through the timing pulleys 90, 91 and the timing belt 92.
In the former case in which the electric motor is connected with the roller through the coupling, the size of the pressure roller mechanism of the longitudinal direction is increased. In the latter case in which the roller and the electric motor are disposed in parallel, the size of the pressure roller mechanism of the transverse direction is increased, and also the size of the height direction is increased, so that the overall size of the winder is increased.
Further, the number of bearings is increased to a value of not less than 4. Accordingly, when the winding operation is conducted at high speed of not less than 4000 m/min, energy loss is remarkably increased, and at the same time an amount of heat generated by the electric motor is increased, so that the lubricant of bearings assembled to the electric motor is quickly deteriorated, and the bearing life is extremely reduced. Further, in the high speed winding operation, the winding speed of which is 7000 m/min, the heat generated by the motor and bearing is transmitted to the roller body, so that the temperature of the roller rises higher than the setting temperature. As a result, the characteristics of a yarn coming into contact with the roller body are changed, and dyeing specks are caused in the latter process.
Next, an idle type pressure roller 80 rotated by a package is shown in FIG. 21, in which the shaft portions 81b are protruded onto both sides of the roller body 81a, and this roller 81 is rotatably mounted on the frame body 13 through the bearing 82.
In the case where the pressure roller 80 is of the idle type, in the same manner as that of the drive type, when a yarn is wound at a high speed of not less than 4000 m/min, the bearing 83 of the bearing section 82 is heated when the roller 81 is rotated at high speed by the tube or package tightly attached to the spindle 2. Therefore, the bracket 84 coming into contact with an outer race portion of the bearing 83 is heated, and at the same time the shaft portion 81b coming into contact with an inner race portion of the bearing 83 is also heated, so that the temperature of end portions of the roller body 81a close to the shaft portion 81b is raised. However, since the bearing section is not forcibly cooled, the amount of heat radiated from the bearing 83 is larger than that radiated from the peripheral surface of the bracket 84. As a result, the lubricator in the bearing is quickly deteriorated, and the life of the bearing 83 is reduced.
When the heat generated by the shaft portion 81b is only radiated from the peripheral surface of the end portion of the roller body 81a, the temperature of the roller can not be immediately lowered, and further the heat in the end portion of the roller body 81a is not transmitted to the center of the roller body 81a. Accordingly, the temperature of the end portion of the roller body 81a becomes higher than the temperature of the center. For this reason, the characteristics of the yarn coming into contact with the portion of the roller, the temperature of which is high, are changed. As a result, dyeing and weaving specks are caused in the process to which the yarn is subjected later.
In the present invention, the first problem to be solved, is described as follows: When the yarn is subjected to the switching operation, tension applied to the yarn fluctuates. Therefore, the yarn is torn off and the yarn switching operation fails, and further a package having uniform characteristics from the most inner to the most outer layer can not be provided.
The second problem is described as follows: It takes a long period of time from when the yarn layer provided on the tube comes into contact with the pressure roller, to when the surface pressure is increased to a predetermined value. Further, it is impossible to accurately detect the time at which feed forward control is switched to feedback control.
The third problem is described as follows: The slippage characteristics of an electric motor and the rotational resistance of a bearing are different between the individual devices. Therefore, it is necessary to measure the slippage and to input a correction coefficient for each winder. Accordingly, it takes much time and labor. Since the correction coefficient is stored in a control unit, the correction coefficient must be inputted again each time a combination of the winder and control unit is changed.
The fourth problem is described as follows: There is a difference between the temperature of the bearing at an initial stage immediately after the start of the operation, and the temperature of the bearing after it has operated over a long period of time. Therefore, the rotational resistance differs, and the slippage of the electric motor is greatly changed. Further, when the rotational resistance of the bearing is changed with age, the slippage of the electric motor is also changed. Accordingly, a difference is caused between the previously measured and inputted slippage, and the substantial slippage. Therefore, the rotational speed of the pressure roller is lowered, and the pressure roller is rotated by a package. As a result, a package of uniform configuration can not be provided.
The fifth problem is described as follows: When the rotational speed of the pressure roller is increased, the pressure roller drives the package, so that the electric motor is heated and may be damaged by an overload.
The sixth problem is described as follows: In a turret type winder, yarn winding tension fluctuates in the yarn switching operation. Therefore, the yarn is torn off or wound around other rollers, and a ratio of success is lowered in the yarn switching operation.
The seventh problem is described as follows: Since the frame body is supported in a cantilever condition, a high moment is applied to the sliding ball bearing, so that the running resistance of the sliding ball bearing is increased and the surface pressure of the pressure roller cannot be accurately controlled, which deteriorates the configuration of a package.
The eighth problem is described as follows: When the frequency of vibration caused by the rotation of the spindle in the yarn winding operation coincides with the natural frequency of the frame body, resonance is caused in the winder, and the yarn layers of the package collapse.
The ninth problem is described as follows: When the frame body is supported by the stopper means, a high moment is applied to the sliding ball bearing, so that a sliding bearing of high allowable moment must be used. As a result, an overall height of the winder is increased.
The tenth problem is described as follows: In a construction in which the drive electric motor is connected with the roller through a coupling, the size of the pressure roller mechanism of the longitudinal direction is increased. In the case where the roller and drive electric motor are provided in parallel, the size of the pressure roller mechanism of the transverse direction or the size of the height direction is increased. As a result, the overall size of the winder is increased.
The eleventh problem is described as follows. The number of bearings is increased to a value of not less than 4. Accordingly, when the spindle is rotated at a high speed of not less than 4000 m/min, energy loss is increased, and at the same time an amount of heat generated by the electric motor is generated. Therefore, the lubricant in the bearings in the electric motor is quickly deteriorated, so that the life of the bearing is extremely reduced.
The twelfth problem is described as follows: In the high speed winding operation in which a yarn is wound at a speed of 7000 m/sec, the heat generated by the electric motor and bearings is transmitted to the roller body. Therefore, the temperature is raised to a value higher than the setting temperature. Accordingly, the characteristics of a yarn coming into contact with the roller body are changed, which causes dyeing and weaving specks in the later process.